Weld line notches

In these blends, ABS s role is to improve flowabihty and reduce cost, while that of PSF is to improve the shape retention at high temperatures. ABS/PSF blends are compatibilized either by phenoxy, EVAc-GMA, or SMA copolymers. They have good processability, high notched Izod impact strength, plateability, hydrolytic stability, and economy. However, they may show poor surface and weld-line strength. Arylon and Mindel A are examples of the commercial ABS/PSF alloys, while Ucardel is an example of PSF blends with SAN. Evolution of ABS/PSF blends technology is summarized in Table 1.19. 

Weld Line (Visible Notch or Colour Change)... 

Improving a weld line (visible notch or colour change)... 

During the filling stage in a injection molding process, molten plastic forces the gas out of the mold cavity from the vent. If the gas can not vent out before the molted plastic fronts meet, then there will be a v-notch formed between the plastic and the mold wall. The locations of the weld lines are usually decided by the part shapes and the gate locations. Weld lines can be eliminated by the following methods, namely. 

With the increasing temperature, the viscosity of the molten plastic decreases, which promotes the flow of the plastic, and reduces the depth of the v-notch of the weld lines. However, degradation of the material strength sometimes occurred if the melting temperature is too high. 

A vapor chamber based rapid heating and cooling system for injection mold is proposed for reducing the weld lines of the plastic products. Tensile test parts and multi-holes plated were tested with this heating and cooling system. The results indicates that the new heating and cooling system can reduce the depth of v-notch as much as 24 times. 

Flow weld lines are formed during molding if two melt flows converge or reunite. A weld line region of a product may be mechanically weakened due to limited molecular chain diffusion across the weld line interface (particularly near the cooler skin), stress concentrations at the bottom of the V-shaped notches at the product surfaces, and different orientations of macromolecules near weld lines caused by the fountain flow at the melt front [6]-[8],... 

The fracture strength of the butt joint welded by the high-current GMA welding process was studied at room and low temperatures using a deep-notch test specimen, 400 mm wide. The edge notches of the specimens were located in the weld metal or along the bond. The test results are shown in Fig. 5. For comparison, the relationship between the fracture strength and the temperature of the base metal is shown with a dashed line. 

Welded joints of secondary sodium stem of FBTR were subjected to Ulttasonic Examination (UE) as po ASME Sec XI, the purpose for winch is to generate base line data for the foture in-service inspection of these joints. Reference p standards having the same matoial and wdd configuration for different pipe outdde diameters wme made. Rectangular notches hadng a dq>th of 10% wall thidcness, 25.4 mm largtfa and 3 mm vndth were made by... 

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